I'm having a issue which is hard to debug. I'm using a Javascript library (the JQuery Flexslider plugin) in a number of different places on my site. It's all working fine except for one particular phone where it doesn't work and slows down everything on the page.
So far, I've only seen it happen on this one device. Other devices of the same type do not have the issue. This person has an iOS that's a few versions out of date and not much memory, so I think it's a memory issue.
An old hack was to move the carousel element that has the issue on the page with Javascript, but I want to find and fix the root issue.
How can I start debugging this? I'm not sure how to test for a memory issue on a device.
If you're on a Mac, then you can plug in and use remote debugging via Safari, where you'll have access to the tools, including the profiler (not sure the state of Safari support in Windows). There are numerous resources for showing how to remotely debug a device, unless it is a really old version of iOS you should be fine, you’ll have to enable the develop menu via settings but after that its plain sailing if you know your debugging tools.
I'd agree that it doesnt really sound like a memory issue, although jQuery tends to be hungry in that respect, I dont know the plugin in question but the quality of plugins is hugely variable in jQuery-land. Old phones and old versions of jQuery certainly never played well together.
When you say one phone, you mean one type of phone + iOS version? The question isnt clear, its almost reads like you have 2 identical phones/os's where 1 works and 1 does not.
If you use Chrome you can use the Heap profiler
First open your developer tool and start recording.
Next start using your page and try to replicate your issue, stop recording and review the stats.
This is likely not a memory issue, but a cpu issue. The way jQuery does animation is processor constrained on older dvices. Factors that are easiest to handle include:
size of the page (html length and complexity)
animation steps, length, and complexity
You have a couple of options here, but the simple answer is you are asking too much of the older processor. Assuming you are using this plugin http://www.woothemes.com/flexslider/ you could try disabling or simplifying some of the transition effects. animation and animationSpeed would be the first I would suggest.
If you are interested in not changing the experience for most users you could consider tying into the start and end functions on the callback api and checking the time it took to perform the first transition, then reinitialize a simpler version of the slideshow for that device.
The hard thing here is there isn't really a right answer. If one of the above options doesn't fix it you're likely looking at choosing/building a different slideshow, degrading the experience for everyone, or determining the best way you feel comfortable with choosing who gets the degraded experience.
Related
I've made a website that displays certain posts from Instagram, Facebook and Twitter. The website shows these posts in card form with certain animations and transitions. It works fine on the desktop but the goal is to run it on raspberry PIs and, when run from one of those, the animations and videos stutter. I want to reduce or eliminate the stutter and I'm considering several approaches:
web workers to offload some of the animation calculations to a separate CPU core
dynamic video compression on the server depending on what device will be playing the video
different animation methods
To figure out if any of these would help I'd want to first figure out what is actually causing the stutter but I don't know how to do this. I need a way to figure out what portion of the slowdown is due to what issue. Like, what's the impact of loading the images/videos, the impact of playing the video, of animating the elements etc. What is the best way of doing this?
Here is the working version of the site if that will help with the suggestions. Note that I'm not highly experienced with JS or programing in general and I was just starting out when I created this so it's far from optimal but now I need to figure out the best way to improve it.
This is probably a performance issue, but it could be something else. If you're using VNC Viewer or some other form of remote desktop, it could be because of that. If it's just wired to a monitor, though, it's most likely the fact that the CPU can't handle it. You could try to install a more lightweight browser, because Chromium can really take a toll on the CPU. Go to Chrome DevTools, and go to the performance tab. This should show you basically everything you need to know. I'm not sure if you're using CSS transitions or something else, so I can't really help you there. You could try NetSurf or Dillo as more lightweight browsers, though.
Can anyone explain why the provided canvas animation stutters? I've created a test stub which demonstrates the problem.
I see the stutter in FF, Chrome, IE on desktop and in FF and Chrome on Android.
Is the stutter due to garbage collection? It seems even raf generates a double on each call which eventually requires gc. If gc is the cause then html5 animation is pretty much doa. Sigh.
The same question was asked a year ago but because I'm a new member I'm not able to contact the author to find out his solution. HTML5 Canvas DrawImage Stutter / Choppiness . It is really too bad there is no way for a new user to get another user's attention, since the author of that other question may have the information I'm looking for, an simply hasn't posted it. I tried posting to his question in an effort to get his attention, but my post there was deleted as a rules violation(which is was). Guess I'm out of options. Chicken and egg problem with rep.
Ok, so after pulling my hair out for 1.5 days I think I have an answer. It appears browsers vsynch to a monitor, which I guess is the point of calling requestAnimationFrame. It appears the synch mechanism can get confused when running on a multi monitor system. I have three monitors. When I disconnect all but one monitor and restart the browser, the problem appears to go away. This kind of makes sense given that the problem manifests sporadically, ie I'm guessing when a given monitor gets out of synch with which ever monitor is providing vsynch to the browser.
Since I'm not certain about this I'm hoping others can confirm or shoot down my theory. I'll continue to (re)test with different monitor configurations, but it would be nice to get confirmation from another brain and set of eyes.
Edit 01: I'm not completely nuts. http://news.softpedia.com/news/Firefox-Nightly-Adds-Support-for-Vsync-for-Smooth-Animations-360245.shtml
Edit 02: Some chrome users/devs has discovered this or a related problem. Finally something might be done with this issue. See https://code.google.com/p/chromium/issues/detail?id=422000. BTW, IE11+ does not have this issue. Started using IE11 for baseline testing, since chrome is having QA issues lately.
Edit 03: Just ran across this q&a which is similar. Good info in the first answer. Chrome requestAnimationFrame issues
I am developing a very game-like web application, and there is a particular requirement that is driving me nuts: I have to show an image for a very short (some hundreds of ms, sometimes even just 25ms, just enough for the user to perceive something when he/she already knows what to look for). This application has to work on Chrome, Firefox and IE9+, but also Android tablets and iPad.
The only reliable way of doing this in desktop browsers I have found is Flash. Using Javascript and html5 canvas in a lot of computers results in the items not even being rendered. On the other hand, Flash doesn't work on the iPad and some Androids, but in those devices, our tests show, the javascript way seems to work just fine. So this is the best solution I have found: grosso modo, if iPad then load_javascript_version() else load_flash_version().
Have you seen anything like this done before? Should I abandon any hope of finding a more maintainable solution?
Thanks a lot.
Haven't tried this particular use case, but a 2D library like KineticJS should be able to do what you need.
There are jQuery functions like timeout: http://www.jquery4u.com/jquery-functions/settimeout-example/ and delay: http://api.jquery.com/delay/
Are you using RequestAnimationFrame in your game loop? If not please read about it and ensure that your image is preloaded when you try to render it.
Mozilla dev RAF api
Most devices and browsers that have hardware accelerated canvas support, should be able to achive as fast as 60 fps fairly, which means you would be able to show an image for a single frame or about 16.7 ms.
I have managed to do similar things using the createjs library which can very easily be set to use the RequestAnimationFrame api.
Createjs ticker RAF
Anyone out there done reserch or have real good experience with 3rd party scroller's for apps running in a webview? Especially with more than one divide that scrolls?? i.e. A webview with a navigation panel and a details panel.
When there is only one divide requiring a scroller, it works smoothly but in the situation above, its very choppy. I'm sure a lot of developers have encountered this issue.
I have tried iScroll (and is best so far) along with other plugins but the quality of the scroll is less than desirable. I can't use iFrames because I need to tweak the style of some HTML docs that are pulled from our server. I've searched online for a way to invoke the native scroller in HTML divides and haven't found a way to. Is there a way and how could I do this?
I've been playing around using API's 9 thru 15 on various devices and I'm not seeing any difference when it comes to the performance of a non-native scroller. I'm currently developing the app on 15 if this is a help to your answer. Also, I have hardware acceleration off and this works best.
I've played with jqm, Sencha, and alike and they seen to have satisfactory scroller's. Does anyone know what they use? The issue why I'm not primarily using any of these platforms is the bulk and other performance issues.
Currently I'm building an app using raw javascript and this is proving to have a significant improvement in performance over all in animations within the webview layouts - Significantly better over any of the big name cross platform solutions. Unfortunately I am not experienced enough to build my own scroller so I need to find an out of the box solution.
Any ideas, leads or solutions so others that are better at writing apps with javascript can have a fighting chance building quality apps would be very appreciated.
With you experiences and experties, please include what API level you were using.
Thnx
I did many tests about this. I won't recommend a third party scrolling based only on HTML because on my experience the problem is not the javascript, but the webview itself:
1) Iframes performance on WebView is weak weak weak. I got a nearly 40% decrease on performance for any (complicated) app just for placing it inside an iframe. Besides, they cause much more problems if you use hardware acceleration.
2) Scrolling of DIVS is acceptable if stuff in divs is simple and SHORT, but the performance decreases as you add more elaborate stuff to scroll. For example, in my case it made a difference to enclose everything in ul/li's (slower) or not (noticeabily faster). However, the feeling is not perfect, ie., if you are used to native scroll, you realise this is not native scroll.
3) Raw scrolling of the body is very good. Besides, you get native-like feedback, such as the glowing effect on overscroll, etc. But mind that this scroll is NOT using javascript, it's just a page bigger than the webview that you let the user to scroll and WebView takes care of it. In my case, this was the only acceptable scroll experience I wanted for my users.
So I came with a mixed solution: I did a JavaScript-callable Java function that would open another webview with requested size like if it was an iframe, so I could open it from HTML and fill with stuff, it was not very difficult to do, and the improvement was awesome.
More things:
4) Scrolling a WebView from Java (scrollTo) was very useful in my case, where I had a huge HTML page loaded (kind of a magazine) to be swipped. Performance if I asked the webview to scroll from Java was much, much, much better than relying on JavaScript to do the scroll.
5) Hardware-Acceleration improves the scroll speed a 100% -setLayerType(HARDWARE)- but to be able to use it you have to keep you html very very simple. stuff like Display:none/block, etc completely break the application (see WebView fails to render until touched Android 4.2.2 for more info)
6) HTML5 animations on big images completely kill the scrolling experience.
7) All this is not valid in a couple months, goole is replacing the rendering engine to "Blink", so who knows what's gonna happen. I am restless.
I am thinking as a challenge i should write a javascript based game. I want sound, images and input. A background to simulate a screen (like 640x480 with all my images in it) would be useful to separate the rest of the page from the 'game'. What should i look at?
Some things i would need
Framecontrol. A way to get the current time (or delta).
Image, displaying it and moving it. How do i display full image. Knowing pixel access may be cool.
Input A way to lock it in a box (like flash does) is cool.
Sound play simple sounds on demand (like when i get a hit). Several sounds at once would be great
Bottlenecks. What are things that will kill the CPU?
Restrictions. What cant i do? I hear i cant 'sleep' to wait. I must set a callback
Good or best pratice. What are good things i can do to either keep speed up or to lower glitch or compatibility problems.
I'm going to answer this looking at things from a mootools javascript perspective:
Framecontrol. A way to get the current time (or delta).
periodical()
Image, displaying it and moving it. How do i display full image.
setStyles()
Input A way to lock it in a box (like
flash does) is cool.
Plain old CSS
Sound play simple sounds on demand
(like when i get a hit).
Swiff, remote();
Bottlenecks. What are things that will
kill the CPU?
Internet Explorer.
Restrictions.
3D ... ?
What are good things i can do ... to
lower glitch or compatibility
problems.
Use a framework.
As a starting point, you may want to write it for Opera, as Opera provides a game canvas that will help you out.
For some examples of games in javascript:
http://dev.opera.com/articles/view/3d-games-with-canvas-and-raycasting-part/
http://my.opera.com/WebApplications/blog/show.dml/200788
This one is interesting, it is demos of games using the canvas element.
http://www.canvasdemos.com/tag/games/
The best way to see where the problems are is to start writing the game, and then you will see what may be a problem. By looking at demos you can get an idea what performance issues they encountered. For example, a full 3D Doom game will have problems, but, as the first article above explains, there are some ways to optimize for javascript.
Once you get it working with Opera, then you can look at Firefox 3.5+ and Safari, as well as Chrome, and see if you can make some changes to have it work on those. How many platforms it works on depends on how much work you want to do for it. For a proof-of-concept pick the easiest browser for your task.
The best place to start would be to get very familiar with the <canvas> tag (it allows you to draw anything on screen)
This may help a lot:
http://benfirshman.com/projects/jsnes/
its an online NES emulator that renders everything on screen - the source is also available
Hope that helps =)